Question

Sue wants to increase 160 by 4%

She writes down

160 x 1.4 = 224

Sue's method is wrong.


a) Instead of multiplying by 1.4, write down

what she should have multiplied by


Bill wants to decrease 160 by 6%

b) Complete the statement below to show how Bill can decrease 160 by 6%

160 × ___ =___

Answer 1

see explanation

Explanation:

An increase of 4% = 104% =
`(104)/(100)` = 1.04

Sue should have multiplied by 1.04

(b)

A decrease of 6% = 94% =
`(94)/(100)` = 0.94 , thus

160 × 0.94 = 150.4

Answer 2

Explanation:

NOTE: Increasing x by p% means multiplying x by (1+p%).

• 4% = 4/100 = 0.04

then

increase 160 by 4% means multiply 160 by (1+4%)

in other words:

1+0.04 = 1.04

increase 160 by 4% means 160 by 1.04

160×1.04 = 166.4

• 160×(1 - 6%) = 160×(1 - 0.06) = 160×0.94 = 150.4